Electric switching apparatus controlled by solar radiation



Jan. '12, 1954 K. SCHWEINGRUBER 2,666,116

ELECTRIC SWITCHING APPARATUS CONTROLLED BY SOLAR RADIATION Filed Nov.19, 1&351 2 Sheets-Sheet 1 F4 Hg. 3

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ELECTRIC SWITCHING APPARATUS CONTROLLED BY SOLAR RADIATION Filed Nov.19, 1951 2 Sheets-Sheet 2 I Z 2211 GIUZOZO J1 SQZiu/eLIgnwbez PatentedJan. 12, 1954 UNITED STATES PATENT OFFICE 2;666,116 ELECTRIC 'swrrcmnaAPPARATUS con- TROLLED BY SOLAR 'RADIATIO'N Kurt Schweingruber, Zurich,Switzerland Application November '19, 1951, Serial No. 257,111

1 Claim.

lating material, being in the lower rounded portion of its two shanksfilled with an electriccom tact fluid, one of the higher ends thereof.in-

tended for exposure .to the sun, exhibits a dark heat-absorbingcoloration, whereby two electric contact elements are provided, of whichonewith balanced co-planar fluid level in the two tube shanks-opens intothe tube above this level and the other below it.

The accompanying drawing shows by way of example a preferred embodimentincorporating the invention.

vFig. 1 is a lateral view of the switching apparatus seen in directionof the arrow I indicated in Fig. .2, V

Fig. 2 is a horizontal section taken .on the line IIII of Fig. 1, V

Fig. .3 is a vertical section taken on the line III-III of Fig. 2,

. Fig. 4 is another vertical section taken on the line IV-IV of Fig. 2,and

Fig. 5 shows a wiring diagram.

In the form illustrated, numerals I and ,2 designate the two shanks of asubstantially U-shaped and sealed tube made of some electricallyinsulating material, say glass, being filled in the lowerrounded'portion with an electric contact fluid 3, say mercury. The shankI has an upward extension Ia which through a bend lb and a descendingsection Ic passes over into a'ho'rizontally disposed tube portion Idwhich at its end carries a spherical enlargement Ie. At location 2a thetube shank 2 is bent off at right angles and merges at its end likewiseinto a spherical enlargement 2b which is frosted externally and exhibitsa dark coloration absorbing the heat rays. Numerals 4 and 5 denote theends of two electric wires passing through the wall of the tube I, 2 andwith balanced co-planar mercury level in the two tube shanks one of saidwires 4 terminates into the tube above said level, and the other 5 belowit.

For protection against mechanical breakage, the portions I, 2, Ia and Isof the tube are arranged in a casing which consists of a cylindric piece6 having a bottom I attached thereto by screws 8 adapted to serve forconnecting the wires 4a, 5a to those I0 and I I brought out of thecasing 6. The cylinder 6 carries a top piece I2 oflarger diameter,attached thereto by screws I3. The top piece I2 is closed by adome-shaped lid I4 having at its underside two leaf springs I5 securedthereon. Said leaf springs engage under tension the inner side of thetop piece I2 '(Fig. 1), thus frictionally holding the lid I l thereto.The Wall or the cylinder 6 is pierced by the tube sections Id and 20within insulating bushes I6 so that the spherical ends I e and 2bintended for exposure to the sun come to lie outside the cylinder 6. 'Toprevent heat losses by convection, say, in the case of ir'l't'ense airmovements, the spherical ends of the tube, filled with an indifferentgas, say nitrogen, are each surrounded by a protective jacket I!permeable to heat rays and consisting, say, of glass. In the exampleillustrated such protective jackets are formed by tubular glass piecesbeing at one end each put onto a rubber disc I8 riding on the tubesections Id, 20. Numeral "I9 designates a pipe clip embracing the casingpart Sand which has a bracket 20.

By means of said bracket I9, 20 the aforedescribed switching apparatusis attached to the outside of the building within the range of thedisplays or shop windows to be protected from solar radiation. As soonas the spherical tube ends Id and 2b become exposed to the sun, the gastherein gets warmed and tends to expand. Due to the frosting anddarkening of the spherical me'm'ber 2a, the gaseous substance thereingets more warmed than the gas in the spherical member I e. As a result,the mercury in the rounded bottom section of the tube shanks I, 2 isdriven up into the extension Ia of shank I, thus closing the currentcircuit between the wire ends 4 and 5 as soon as the mercury column intube shank I or Ia reaches the level of the wire end 4.

The aforedescribed switching apparatus may either be put into thecircuit of an alarm device or into the control circuit of a motor foractuating sun blind disposed over window displays to be protected. Assoon as the circuit between the wire ends 4' and 5 becomes closed by themercury column rising in shank Ia, a sun blind-actuating motor willeither be inserted or an acoustic, optic or combined alarm signal betripped, thus drawing the attention to the fact that the displays orshop windows are exposed to the sun and that the blinds should beactuated.

As soon as the spherical members Ie and I b are no longer exposed to thesun, the gas therein will cool and thus cause the mercury column in thetube shank to drop. As soon as the level of the mercury column in thetube shank la falls below the wire end 4, the current circuit betweenthe contact elements 4 and 5 will be interrupted and thus an alarmsignal be tripped, or the motor for raising the sun blinds be set inoperation. Due to the fact that the spherical member 2b is not suddenlycooled after the sun has ceased to act and that consequently contractionof the gas within the spherical member cannot instantaneously takeplace, the fluid contact between the contact elements 4, 5 is preventedfrom being broken by temporary radiation caused by a cloud passingacross the sun. As a result of the darkening of one spherical member 2bthe switching apparatus is only set in action by heat radiation, but notby heat convection, inasmuch as both spherical members le and 2b areevenly warmed by convection, so that the rise in gas pressure in bothmembers ensues evenly and the level of the contact fluid remainsundisturbed.

Fig. 5 diagrammatically shows the aforedescribed switching apparatus asput into the wiring diagram of an installation. Therein Sch marks theswitching apparatus, T. a transformer, TI and T2 the wires connected tothe secondary coil, Tkl to T105 are five thermal contacts with thepertinent heating elements HI to H5, S being a fuse, Sr a buzzer, G aglowing lamp, L and LI the line conductors, L2 and L3 the wires leadingto contactor and. motor for actuating the sun blinds, R is a relay andKI and K2 its contacts for changing over.

The action of the system illustrated in the diagram is as follows:. a

interruption of solar After about two minutes it engages the latter,

thus setting alive the heating coil H5 of the thermal contact Th5, i. e.via Tl of thermal contact T704, further via L6, C6, Z3, Z4, C4, Z2, LT,

Zl, Cl, L8, H5 to T2. After about two minutes the thermal contact Tk5changes over, thus causing the contact stud Z5 to engage the element C8and to close a circuit of TI, Z5, C8. L5 via H4 to T2, whereby the coilH4 01 the thermal contact T704 will be warmedup. Incidentally thecontact Whenthe solar heat acts upon the switching apparatus Sch,thecircuit connected to the terminals TI and T2 of the secondary coil ofthe transformer is closed. Incidentally the heating coil HI of thethermalcontact Tkl gets warmed, thus causing the contact stud Zl, say ofa bimetallic strip, to bend upwards and move clear of the contactelement Cl. After about two minutes the contact stud Zl engages thecontact element C2. Thus a further circuit will be closed which extendsfrom the secondary coil of the I transformer via wire TI, contactelement C2, contact tongue Zl through the heating coil H2 of thethermocontact Th2 and over the wire T2 back to the transformer. Therebythe heating element H2 gets warmed, thus causing the contact stud Z2 tomove clear of the contact element C3 and towards'the contact element C4.After about two minutes the contact stud Z2 engages the contact elementC4, thus closing a further circuit: Tl, C2, Zl, L1, Z2, 04 and via relayR to T2. A branch of this current passes through wire L4, contact studZ3, contact element C5, wire L5 via buzzer Sr to T2, thus setting thebuzzer in operation. From the wire L4 a current branch passes throughthe heat ing element H3 of the thermalcontact TN to T2, thus warming upsaid element and causing the contact stud Z3 to move towards the contactelement C6. As the contact stud Z3 moves clear of the element C5, thecircuit of the buzzer Sr will be interrupted, i. e. about seconds afterits starting. After further 30 seconds approximately the contact stud Z3engages the element C6, thus closing the following guarding circuit forrelay R T2, R, L4, Z3, C6, L5, T704 via C1+C9 and Z5 +Z4 to Tl. Thus theworking condition of.

the system will be established which lasts so long as the switchingapparatus Sch is exposed to the sun. The relay R includes twochange-over contacts for 220 volts 4 amperes. Its contact stud Z4 movesclear of the element C9 to engage then the contact element CID after awhile. When the contact stud Z4 moves clear of the contact element C9,the relay R becomes dead. Thereby the contactor connected to contact Klis again actuated so that the motor is now caused to rotate in oppositedirection, thus raising the sun blinds. Simultaneously the signal lamp Glying on contact K2 is extinguished. The thermal contact T104 workssomewhat quicker than the thermal contacts Tkl, T702, Th3 andTk5. Thecontact stud Z4 engages the contact element CIU after about fifteenseconds, the" circuit being reclosed via buzzer and set in opera; tion.This gives the signal that the sun blinds will be raised. This signallasts about 20 seconds.

Upon insertion of the thermal contact T704 as aforementioned, thethermal contacts Tk3, TM and Tk5 also become dead and cool off. Thusafter about thirty seconds the circuit Tl will be interrupted from T705via Z5, C8,,L5 and H4. to T2. With the cooling of the heating coil H4the circuit of the buzzer will be interrupted; Upon cooling of allthermal contacts the apparatus is again set atrest.

The retardation for switching-on the installation lasts about three anda half minutes without the retardation .of the switching apparatus,whereas the retardationfor the switching-off takes about four minutes.

A further switch may be put into the aforede scribed diagram, by meansof which the installation may be changed over from automatic to manualoperation. When set on manual operation the motor for raising theblindswill not be automatically inserted, but alarm signals will be actuated,whereupon the motor should be inserted by hand.

In connection with the different diameters of. the tube shanks Iaand 2the volume of both spherical members Ie and 2b is so dimensioned; thatwith even changes of the outside tempera- An electric switchingapparatus for control by solar radiation, comprising a verticallyarranged tube of electrical insulating material and having at both itsupper and lower ends U-bends to provide upwardly and downwardlyextending vertical leg portions, a spherical enlargement at the end ofeach leg portion and in communication therewith; one only of saidspherical enlarge;

ments having its external surface frosted and darkened to selectivelyabsorb a greater proportion of incident radiation than that absorbed bythe other-enlargement, a body of mercury in the lower bend of saiddevice, the remainder thereof containing a gaseous atmosphere, andrespective contacts, one disposed in the lower bend of said.

sures in said enlargements are equal, whereby 1 said body of mercurywill complete a connection between said contacts in response to solarradiation impinging upon said darkened enlargement.

KURT SCHWEINGRUBER.

References one}; in the file of this patent UNITED- STATES PATENTS1,819,077 DeFilippi Aug. 18, 1931

